libusb: needs thread support

libusb needs thread support, and so do other packages that depend on it.

[thomas.petazzoni@free-electrons.com: adds threads dependency to
libnfc-llp, which selects libnfc.]

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>